Doing a google search, I also found one on Pinterest (though it links to Ebay) so you best bet is ebay.

If it turns out that the product is not to your liking (it is from China, renown for mass producing products) Then you could try requesting someone to custom build it for you (maybe you can find someone to do this on Etsy? I don't know of too many other sites)

If treated right, leather can last you a very long time. If you invest in one of these bags, I would highly recommend buying some saddle soap for the time-to-time maintenance.

PS: If you want something that looks a little different than what i listed, I would definitely try looking in Etsy. But be warned! Prices can get insane (saw some for 1,000+), though there are $59 bags if you filter/look through

Thanks for sharing this question, as I am now considering buying one of these bags (classy and good life-span bags)